Prevent hidden inputs from taking up space on the page (#3202)

Author: camertron

.changeset/two-badgers-suffer.md

@@ -0,0 +1,5 @@
+---
+'@primer/view-components': patch
+---
+
+Prevent hidden inputs from taking up space on the page

app/forms/horizontal_form.rb

@@ -3,6 +3,8 @@
 # :nodoc:
 class HorizontalForm < ApplicationForm
   form do |my_form|
+    my_form.hidden(name: :token, value: "abc123")
+
     my_form.group(layout: :horizontal) do |name_group|
       name_group.text_field(
         name: :first_name,

app/lib/primer/forms/dsl/hidden_input.rb

@@ -27,6 +27,10 @@ def type
         def supports_validation?
           false
         end
+
+        def hidden?
+          true
+        end
       end
     end
   end

app/lib/primer/forms/group.rb

@@ -18,9 +18,12 @@ def initialize(inputs:, builder:, form:, layout: DEFAULT_LAYOUT, **system_argume
         @layout = layout
         @system_arguments = system_arguments
 
+        @system_arguments[:display] = :none if inputs.all?(&:hidden?)
+
         @system_arguments[:classes] = class_names(
           @system_arguments.delete(:classes),
-          "FormControl-horizontalGroup" => horizontal?
+          "FormControl-horizontalGroup" => horizontal?,
+          "FormControl-spacingWrapper" => !horizontal? && inputs.size > 1
         )
       end
 

test/lib/primer/forms_test.rb

@@ -172,6 +172,12 @@ def test_renders_horizontal_group
     assert_selector ".FormControl-horizontalGroup .FormControl", count: 2
   end
 
+  def test_hidden_items_wrapped_in_display_none
+    render_preview :horizontal_form
+
+    assert_selector ".d-none input[type=hidden]", visible: :hidden
+  end
+
   def test_renders_multi_input
     render_preview :multi_input_form